New staining methods for semithin sections of tissues of Seriola dumerili embedded in methacrylate.

Semithin sections of different tissues of Seriola dumerili R. Embedded in glycol methacrylate, were stained with two staining methods normally used in conventional haematology and histology: Gutierrez's cytopanchrome and Gutierrez's polychrome V.O.F. The results observed in all tissues embedded in this resin and stained with V.O.F. are satisfactory and comparable, as to staining affinity, to those obtained on paraffin-embedded tissues. Gutierrez's trichrome stain appears to be a useful tool in the study of oogenesis for detecting changes in staining according to cellular structure and maturation stage. The results observed with cytopanchrome are similar to those obtained with toluidine blue in glycol methacrylate-embedded tissues. The use of these two staining techniques, requires no previous oxidation, alkali treatments, high temperatures or removal of the embedding medium. Furthermore, both dyes can be used at the same time: in this case, cytoplasm of previtellogenic oocytes showed a stronger affinity for cytopanchrome, and were more intensely stained by V.O.F. as the vitellogenesis of Seriola dumerili progressed. Both stain, and especially the cytopanchrome one, also are available for staining the liver, gills and testis.